What are insulin and proinsulin?

Sugar hormones. Insulin is a major regulator of glucose levels. Insulin promotes the uptake of glucose, particularly by muscle and fat cells. This is why we use Insulin therapy in diabetes, as an Insulin injection will force glucose levels to fall. ProInsulin is a precursor of the Insulin molecule as it is being produced in the pancreas. Small amounts of proInsulin are detectable in the blood in this way.